This application claims the benefit of Japanese Application No. 2000-361714 filed in Japan on Nov. 28, 2000, the contents of which are incorporated herein by reference.
1. Field of the Invention
This invention relates to a lens driving device which performs movement and aperture opening and closing of a lens optical system in an optical device.
2. Description of the Related Art
The disclosure in Japanese Patent Laid-open No. 11-287941, regarding a lens driving device which performs movement and aperture opening and closing of a lens optical system, applied to electronic cameras, photoenlargers, and other optical equipment of the prior art, relates to a lens driving method which performs lens movement driving and aperture driving by means of a single driving source.
In the above conventional lens driving device, a dead zone portion is provided in the cam formed in the lens barrel. When the lens moves and is positioned in the above dead zone portion, the aperture is opened and closed by rotation of the above lens barrel. By reversing rotation of the lens barrel, moving the lens in the backward direction with the above aperture opening maintained, modification of the magnifying power, focus driving, and aperture opening and closing, can each be performed by a single driving source.
However, in the lens driving device disclosed in the above-mentioned Japanese Patent Laid-open No. 11-287941, when setting the aperture the lens must be returned to the initial position, and when combining an arbitrary aperture value with a specific lens position, a considerable time is required. Also, a driving plate must be used when performing aperture driving, so that the outer diameter of the lens barrel is increased, and there is the problem that the equipment in which the above device is incorporated increases in size.
This invention was devised in order to resolve the above-mentioned problems, and has as an object to provide a lens driving device which enables the setting of the combination of a prescribed zoom value and an arbitrary aperture value, by means of a simple configuration.
A lens driving device according to one aspect of this invention comprises a lens optical system having a moving lens group movable along a direction of an optical axis, and a focal length which can be altered in stages among a plurality of values; a moving lens group frame holding the moving lens group; an aperture device provided within the lens optical system and having an aperture value which can be modified; a single driving source for changing the focal length value of the lens optical system and the aperture value of the aperture device; and a driving member driven by the single driving source for performing driving to move the moving lens group frame to achieve a desired focal length value of the lens optical system from among the plurality of focal length values, and for then performing driving to change the aperture value of the aperture device while maintaining the desired focal length value; whereby the driving member is driven by the single driving source, and by this means the lens optical system is driven and the aperture device is driven.
Another lens driving system according to a second aspect of this invention comprises at least two moving lens group frames, each capable of different movement in an optical axis direction; an aperture device provided in one of the moving lens group frames; a cam member including: (i) at least two lens driving cams each having a first cam portion and a second cam portion that are formed successively to drive corresponding moving lens groups, and (ii) a third cam portion formed separately from the lens driving cams; and a single driving source for driving the cam member to drive and displace the moving lens group frames and to drive the aperture device for changing an aperture value; wherein the first cam portion is provided in a range in which the moving lens group frames are driven and displaced in the optical axis direction, the second cam portion is provided in a range in which the moving lens group frames are not driven and displaced in the optical axis direction, and the third cam portion drives the aperture device to change the aperture value when the moving lens group frames are in a state of not being displaced in the optical axis direction due to the moving lens group frames being in the range of the second cam portion; whereby the cam member is driven by the single driving source, and by this means the moving lens group frames are driven and the aperture device is driven.
Other features and advantages of this invention will become clear through the following explanation.